Number of tilings of a 3 X n rectangle using dominoes and right trominoes.

Terms

a(0) =1a(1) =0a(2) =5a(3) =8a(4) =55a(5) =140a(6) =633a(7) =1984a(8) =7827a(9) =26676a(10) =99621a(11) =351080a(12) =1283247a(13) =4583580a(14) =16611505a(15) =59652624a(16) =215457835a(17) =775371268a(18) =2796772765a(19) =10073343672a(20) =36315180295a(21) =130843331180a(22) =471599612393